Sixty to eighty per cent of the software life-cycle cost is spent on the software maintenance phase because software maintenance is usually more difficult than original development and legacy systems are generally large and complex. Software reuse has recently been considered as a best solution to enhance the productivity of a software development team and to reduce maintenance costs. In addition, Software Configuration Management (SCM) is a central part of software maintenance as it is associated with changing existing software and is a discipline for controlling these changes. Thus, both software reuse and SCM have been proposed for making a significant improvement in productivity, quality and cost. However, so far these two technologies have been investigated separately. In order for software reuse and SCM to produce effects by synergy, both approaches require to be introduced into a maintenance environment together. Since software reuse and SCM, and software reuse and software maintenance have many similarities in their activities, these disciplines can be integrated within a software maintenance environment. This research has therefore developed an integrated process model for 'Maintenance with Reuse (MwR)', that supports SCM for a reuse library which is actively maintained for use in a software maintenance environment. This thesis addresses an integrated process model called the MwR model and its prototype tool TERRA (Tool for Evolution of a Reusable and Reconfigurable Assets Library) that consist of a configuration management (CM) process, reuse process, maintenance process and administration of a reuse library. The MwR model and TERRA provide reusers and maintainers with many activities of these four processes such as classifying, storing, retrieving, evaluating, and propagating reusable components, including controlling changes to both reusable components and existing systems. The process model of an integrated approach has been developed and validated using Process Weaver. The TERRA tool has been implemented on the WWW so that the prototype can provide portability, traceability, integration with existing tools, and a distributed maintenance environment. The TERRA prototype has been tested and evaluated through a scenario based case study. Several scenarios based on real data have been created and used for the case study so that an organisation can apply the model and tool to its maintenance environment without many problems. The software maintenance community is facing serious problems with legacy systems, such as a ever increasing frequency of changes and backlogs, lack of integrated tools and methods, and lack of software maintenance support environments. The control and management of changes to the software components in a reuse repository are crucial to successful software development and maintenance. If the component is being used in multiple systems effects of uncontrolled change are more critical. However, reuse libraries and servers currently available have not been successful as they do not support further development or maintenance of the reusable components. In addition, most of them are not sophisticated since they have not been linked to a development/maintenance environment. The integrated model of MwR can overcome many problems that exist in software maintenance and reuse through introduction of SCM functionalities into a maintenance environment. Thus, the integration of these common activities will greatly contribute to enhancing the productivity and quality of software, and will additionally lead to reducing the costs and backlogs of changes within a maintenance environment.